David Cameron will on Monday announce an extra £800m to boost Britain's surveillance and intelligence operations, including more resources for special forces, as the UK steps up its response to global terrorism and hostage taking.

The extra funding, to be announced by the prime minister during a visit to the Farnborough air show, is expected to allow Britain to procure more drones to help monitor suspected terrorists.

Cameron will announce that "prudent budget management" in the Ministry of Defence since 2010 has allowed the government to invest an extra £1.1bn in capabilities for the armed forces.

The £800m will be spent on intelligence, surveillance, target acquisition and reconnaissance.

There will also be a £300m investment in existing MoD projects such as new E-Scan radar for Typhoon aircraft and the purchase of the ice patrol ship HMS Protector.

"Because of the difficult decisions we have taken to tackle the deficit, we are able to make these vital investments in our defence capabilities.

"We are also taking action to sustain our thriving defence industry, as part of our long-term economic plan to back business, create jobs and secure a brighter future for hardworking people."

Alison Seabeck, shadow defence minister, said: "We will wait to see further details but it's right that we must maintain Britain's capabilities and support our defence industry … David Cameron should clarify whether this is new funding or underspend from previous years which we were previously told was earmarked for existing projects."